libweston: Convert remaning destroy signals

Replaces potential corruption signal emit call sites with the more safer
weston_signal_emit_mutable().

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>

libweston/compositor.c

@@ -2267,7 +2267,7 @@ weston_view_destroy(struct weston_view *view)
 {
 	struct weston_paint_node *pnode, *pntmp;
 
-	wl_signal_emit(&view->destroy_signal, view);
+	weston_signal_emit_mutable(&view->destroy_signal, view);
 
 	assert(wl_list_empty(&view->geometry.child_list));
 
@@ -2378,7 +2378,7 @@ weston_buffer_destroy_handler(struct wl_listener *listener, void *data)
 	struct weston_buffer *buffer =
 		container_of(listener, struct weston_buffer, destroy_listener);
 
-	wl_signal_emit(&buffer->destroy_signal, buffer);
+	weston_signal_emit_mutable(&buffer->destroy_signal, buffer);
 	free(buffer);
 }
 
@@ -5593,7 +5593,7 @@ weston_head_detach(struct weston_head *head)
 WL_EXPORT void
 weston_head_release(struct weston_head *head)
 {
-	wl_signal_emit(&head->destroy_signal, head);
+	weston_signal_emit_mutable(&head->destroy_signal, head);
 
 	weston_head_detach(head);
 
@@ -6927,7 +6927,7 @@ weston_output_release(struct weston_output *output)
 
 	output->destroying = 1;
 
-	wl_signal_emit(&output->user_destroy_signal, output);
+	weston_signal_emit_mutable(&output->user_destroy_signal, output);
 
 	if (output->idle_repaint_source)
 		wl_event_source_remove(output->idle_repaint_source);
@@ -8208,7 +8208,7 @@ weston_compositor_destroy(struct weston_compositor *compositor)
 	/* prevent further rendering while shutting down */
 	compositor->state = WESTON_COMPOSITOR_OFFSCREEN;
 
-	wl_signal_emit(&compositor->destroy_signal, compositor);
+	weston_signal_emit_mutable(&compositor->destroy_signal, compositor);
 
 	weston_compositor_xkb_destroy(compositor);